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[ << ] [ < ] [ Home ] [ > ] [ >> ] 10. Configuring the BootloaderContent:Now that your kernel is configured and compiled and the necessary system configuration files are filled in correctly, it is time to install a program that will fire up your kernel when you start the system. Such a program is called a bootloader. For AMD64, Gentoo Linux provides GRUB and LILO. But before we install the bootloader, we inform you how to configure framebuffer (assuming you want it of course). With framebuffer you can run the Linux command line with (limited) graphical features (such as using the nice bootsplash image Gentoo provides). If you have configured your kernel with framebuffer support (or you used genkernel default kernel configuration), you can activate it by adding a a video statement to your bootloader configuration file. First of all, you need to know your framebuffer device. You should have used uvesafb as the VESA driver. The video statement controls framebuffer display options. It needs to be given the framebuffer driver followed by the control statements you wish to enable. All variables are listed in /usr/src/linux/Documentation/fb/uvesafb.txt. The most-used options are:
The result could be something like video=uvesafb:mtrr:3,ywrap,1024x768-32@85. Write this setting down; you will need it shortly. Now continue by installing GRUB or LILO. Understanding GRUB's terminology The most critical part of understanding GRUB is getting comfortable with how GRUB refers to hard drives and partitions. Your Linux partition /dev/sda1 will most likely be called (hd0,0) under GRUB. Notice the parentheses around the hd0,0 - they are required. Hard drives count from zero rather than "a" and partitions start at zero rather than one. Be aware too that with the hd devices, only hard drives are counted, not atapi-ide devices such as cdrom players and burners. Also, the same construct is used with SCSI drives. (Normally they get higher numbers than IDE drives except when the BIOS is configured to boot from SCSI devices.) When you ask the BIOS to boot from a different hard disk (for instance your primary slave), that harddisk is seen as hd0. Assuming you have a hard drive on /dev/sda and two more on /dev/sdb and /dev/sdc, /dev/sdb7 gets translated to (hd1,6). It might sound tricky and tricky it is indeed, but as we will see, GRUB offers a tab completion mechanism that comes handy for those of you having a lot of hard drives and partitions and who are a little lost in the GRUB numbering scheme. Having gotten the feel for that, it is time to install GRUB. To install GRUB, let's first emerge it:
Although GRUB is now installed, we still need to write up a configuration file for it and place GRUB in our MBR so that GRUB automatically boots your newly created kernel. Create /boot/grub/grub.conf with nano (or, if applicable, another editor):
Now we are going to write up a grub.conf. Below you'll find two possible grub.conf for the partitioning example we use in this guide. We've only extensively commented the first grub.conf. Make sure you use your kernel image filename and, if appropriate, your initrd image filename.
If you used a different partitioning scheme and/or kernel image, adjust accordingly. However, make sure that anything that follows a GRUB-device (such as (hd0,0)) is relative to the mountpoint, not the root. In other words, (hd0,0)/grub/splash.xpm.gz is in reality /boot/grub/splash.xpm.gz since (hd0,0) is /boot. Besides, if you chose to use a different partitioning scheme and did not put /boot in a separate partition, the /boot prefix used in the above code samples is really required. If you followed our suggested partitioning plan, the /boot prefix it not required, but a boot symlink makes it work. In short, the above examples should work whether you defined a separate /boot partition or not. If you need to pass any additional options to the kernel, simply add them to the end of the kernel command. We're already passing one option (root=/dev/sda3 or real_root=/dev/sda3), but you can pass others as well, such as the video> statement for framebuffer as we discussed previously. If your bootloader configuration file contains the real_root parameter use the rootflags parameter to set root filesystem mount options. In the case where real_root defines the root mount point, the real_rootflags parameter should be used. If you're using a 2.6.7 or higher kernel and you jumpered your harddrive because the BIOS can't handle large harddrives you'll need to append sda=stroke. Replace sda with the device that requires this option. genkernel users should know that their kernels use the same boot options as is used for the Installation CD. For instance, if you have SCSI devices, you should add doscsi as kernel option. Now save the grub.conf file and exit. You still need to install GRUB in the MBR (Master Boot Record) so that GRUB is automatically executed when you boot your system. The GRUB developers recommend the use of grub-install. However, if for some reason grub-install fails to work correctly you still have the option to manually install GRUB. Continue with Default: Setting up GRUB using grub-install or Alternative: Setting up GRUB using manual instructions. Default: Setting up GRUB using grub-install To install GRUB you will need to issue the grub-install command. However, grub-install won't work off-the-shelf since we are inside a chrooted environment. We need to create /etc/mtab which lists all mounted filesystems. Fortunately, there is an easy way to accomplish this - just copy over /proc/mounts to /etc/mtab, excluding the rootfs line if you haven't created a separate boot partition. The following command will work in both cases:
Now we can install GRUB using grub-install:
If you have more questions regarding GRUB, please consult the GRUB FAQ or the GRUB Manual. Continue with Rebooting the System. Alternative: Setting up GRUB using manual instructions To start configuring GRUB, you type in grub. You'll be presented with the grub> grub command-line prompt. Now, you need to type in the right commands to install the GRUB boot record onto your hard drive.
In the example configuration we want to install GRUB so that it reads its information from the boot partition /dev/sda1, and installs the GRUB boot record on the hard drive's MBR (master boot record) so that the first thing we see when we turn on the computer is the GRUB prompt. Of course, if you haven't followed the example configuration during the installation, change the commands accordingly. The tab completion mechanism of GRUB can be used from within GRUB. For instance, if you type in "root (" followed by a TAB, you will be presented with a list of devices (such as hd0). If you type in "root (hd0," followed by a TAB, you will receive a list of available partitions to choose from (such as hd0,0). By using the tab completion, setting up GRUB should be not that hard. Now go on, configure GRUB, shall we? :-)
If you have more questions regarding GRUB, please consult the GRUB FAQ or the GRUB Manual. Continue with Rebooting the System. LILO, the LInuxLOader, is the tried and true workhorse of Linux bootloaders. However, it lacks some features that GRUB has (which is also the reason why GRUB is currently gaining popularity). The reason why LILO is still used is that, on some systems, GRUB doesn't work and LILO does. Of course, it is also used because some people know LILO and want to stick with it. Either way, Gentoo supports both, and apparently you have chosen to use LILO. Installing LILO is a breeze; just use emerge.
To configure LILO, you must create /etc/lilo.conf. Fire up your favorite editor (in this handbook we use nano for consistency) and create the file.
Some sections ago we have asked you to remember the kernel-image name you have created. In the next example lilo.conf we use the example partitioning scheme. There are two separate parts:
Make sure you use your kernel image filename and, if appropriate, your initrd image filename.
If you need to pass any additional options to the kernel, add an append statement to the section. As an example, we add the video statement to enable framebuffer:
If you're using a 2.6.7 or higher kernel and you jumpered your harddrive because the BIOS can't handle large harddrives you'll need to append sda=stroke. Replace sda with the device that requires this option. genkernel users should know that their kernels use the same boot options as is used for the Installation CD. For instance, if you have SCSI devices, you should add doscsi as kernel option. Now save the file and exit. To finish up, you have to run /sbin/lilo so LILO can apply the /etc/lilo.conf to your system (i.e. install itself on the disk). Keep in mind that you'll also have to run /sbin/lilo every time you install a new kernel or make any changes to the menu.
If you have more questions regarding LILO, please consult its wikipedia page. You can now continue with Rebooting the System. Exit the chrooted environment and unmount all mounted partitions. Then type in that one magical command you have been waiting for: reboot.
Of course, don't forget to remove the bootable CD, otherwise the CD will be booted again instead of your new Gentoo system. Once rebooted in your Gentoo installation, finish up with Finalizing your Gentoo Installation. [ << ] [ < ] [ Home ] [ > ] [ >> ] The contents of this document are licensed under the Creative Commons - Attribution / Share Alike license. |
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